Automatic regulation for engine cooling means



May 25, 1937. -|.c. NISSEN AUTOMA'I'IC REGULATION FOR ENGINE COOLINGMEANS 2 Sheets-Sheet 1 Filed Sep'li. 22, 1936 ATTORNEY y 5, 1937. H. c.NISSE N 2,081,762

AUTOMATIC REGULATIQN FOR ENGINE COOLING MEANS Filed Sept. 22, 1936 2Sheets-Sheet 2 J INVENTOR.

' HZUCMSSE'J IZ m i M A TTORNEY 1 and velocity of cooling air passingthrough the j Patented May 25, 1937 AUTOMATIC REGULATION FOR ENGINECOOLING MEANS South Glastonbury, Conn.,

Harry G. Nissen,

, assignor to United Aircraft Corporation,

Hartford, Conn., a corporation of Delaware Application September 22,1936, Serial No. 101,961

14 Claims.-

' This invention relates to improvements in engine cooling means, andhas particular reference to cooling means for an air-cooled internalcombustion engine such as commonly used for the propulsion of airplanes.

An object of the invention resides in the provision of means forautomatically controlling the engine cooling arrangement in accordancewith the operating conditions of the engine and the condition of thosefactors which afiect the amount engine.

A further object of the invention resides in the provision of means forautomatically controlling the engine cooling apparatus in accordancewith the factors of airplane speed, engine power output, and thetemperature of the engine cooling air to provide desired enginetemperatures under various engine operating conditions.

A still further object resides in the provision of means in combinationwith a baiiled air-cooled engine inclosed in a drag reducing cowlprovided with cowl flaps of means for automatically adlusting the flapsto preserve a ratio between engine temperature and flap induced dragconsistent with maximum speed and economy in operation.

Other objects and advantages will be more partichlarly pointed outhereinafter or will become apparent as the description proceeds.

In the accompanying drawings in which like reference numerals are usedto designate similar parts throughout, there is illustrated a suitablemechanical embodiment of what is now considered to be the preferred formof the idea of the invention. The drawings, however, are for the purposeof illustration only and are not to be taken as limiting the inventionthe scope of which is to be measured entirely by the scope of theappended claims.

In the drawings,

Fig. 1 is a partly schematic elevational view of a radial air-cooledinternal combustion engine of the type commonly. employed for thepropulsion of airplanes, an engine inclosing cowl and cowl flaps beingschematically shown in section;

Fig. 2 is a partly schematic perspective view of a mechanism constructedaccording. to the idea of this invention for controlling the cooling ofthe engine; and i Fig. 3 is a' schematic' illustration of the coolingcontrolling mechanism showing the wiring diagrams used for theelectrical portion of the de- East REISSUED W JAN 2f 194 internalcombustion engine of the type commonly employed for the propulsion ofairplanes. It is to be understood, however, that the invention is notlimited in its application to an engine of the particular typeillustrated but may be applied to various types of air-cooled engines.

The engine in the arrangement-illustrated is mounted upon a mountingring l2 supported upon the vehicle, such as an airplane, by a suitableframework, generallyindicated at I4, and is surrounded by an open endeddrag reducing ring cowl, generally indicated at l6. In case of anaircraft engine as illustrated, the engine drives a suitable propellerl8 ordinarily carried upon the front end of the engine at the forwardend of the airplane. Between the propeller and the engine the cowl I6 isprovided with a cooling air inlet opening 20 and at the rear end isprovided with a gill opening adjacent. to the fire wall 22, the gillopening being controlled by a set of movable trailing edge cowl flaps24. In line with the engine cylinders there is provided a set ofpressure bafiles 26 for restricting the flow of engine cooling airthrough the cowl to the finned cooling surfaces of the engine cylinders.

For a more detailed description of suitable pressure bafiies, referencemay be had to Patent No.

2,031,541 issued February 18, 1936 to A. L. Mac- Clain, and for adetailed description of a suitable set of cowl trailing edge flapsreference may be had to application Ser. No. 705,094 filed January 3,1934 by R. B. Beisel and A. L. MacClain. The baflles 26 are effective tocreate a pressure differential between the cooling air contained in thecompartment within the cowl l6 at the forward or propeller side of thebaiiles and the air contained in the compartment within the cowl at therear of the baflies. As the baflies are arranged to radically restrictthe flow of cooling air through the engine, a large pressuredifferential can be built up between the forward and rear cowlcompartments, which pressure differential is utilized to create a highvelocity in the stream of cooling air flowing along the cooling surfacesof the engine cylinders.

The pressure dlfierential between the forward and rear cowlcompartmentsand consequently, the velocity of the cooling air stream,can be controlled by altering the angular position of the set of cowlflaps 24. Thus when the flaps are stream flowing over the outside of thecowl which 55 tends to lower the pressure at the rear ends of the cowlflaps and thus impose a partial vacuum upon the rear cowl compartment tomaterially increase the pressure differential between the forward andrear compartments within the cowl. When the flaps are moved inwardly,the induction effect of the air stream is first decreased, and withcontinued inward movement of the flaps the induction effect is entirelylost and the gill opening is decreased in area to a degree at which itrestricts the flow of cooling air from the rear compartment. Under-suchconditions, the pressure differential between the forward and rear cowlcompartments may be reduced or, in an extreme case,

the pressures may be equalized so that little or no cooling of theengine would be accomplished. From the above discussion, it is obviousthat the cooling effect upon the engine of the air entering the cowlopening 28 may be controlled within extremely wide limits by varying theangular position of the set of cowl flaps 24. It has been found inpractice that the cooling eifect of the air stream can be accuratelycontrolled over the entire operating range of the engine to provide theexactamount of cooling consistent with .best engine operation andrelatively minimum airplane drag at all engine operating conditions. I

According to previous practice, the cowl flaps have ordinarily beensubject only to manual control so that it has been necessary for theoperator of the vehicle to watch the engine temperature indicator andadjust the cowl flaps to obtain the best operating conditions at thetemperatures indicated. As explained aboveythe present invention has forits object the provision of an automatic control for engine coolingthrough automatic actuation of the cowl flaps to provide a more accurateand consistent relation between engine cooling requirements and thecooling effect produced and to relieve the operator'of the vehicle fromthe additional burden of having to watch the engine temperatures andcontrol the cooling arrangement accordingly.

-The objects of the invention are accomplished by the provision of anautomatic mechanism, generally indicated at 28, which is made responsiveto the power output of the engine and to the pressure differentialexisting upon the opposite sides of the pressure baflle system 26. Thismechanism, in response to the pressure diiferential and the enginehorsepower, controls a suitable device,

generally indicated at 30, which is effective to' move the cowl flaps 24to various angular positions and retain them in a desired position forthe cooling effect required under all operating conditions. While thedevice 30 has been illustrated as a reversible electric motor and ascrew jack operated thereby, a hydraulic motor or other suitable poweroperated device is within the scope of the invention.

The control unit 28 is particularly illustrated in Fig. 2 and includesin general a pair of expansible metal bellows 32 and 34 and an electriccontact switch, generally indicated at.36, mounted in a suitable casing38. I

The interior of the bellows 32 is connected by means of a suitableconduit 40 with the forward side of the baflie system 26 to render thebellows 32 responsive to the pressure in the compartment in the forwardportion of the engine cowl. The interior of the bellows 34 is connectedby a similar conduit 42 with the interior of an' engine intake manifold44 to render the bellows 34 responsive to the horsepower output of theengine. As clearly a pivotally mounted link member or bar 46 which hasmounted thereon intermediate its length the electric contact, generallyindicated at 36.

The contact 36 is a double contact having two contact elements 48 and-58carried by the link or bar 46 and an intermediate contact 52 carriedupon the free end of a thermostatic element 54 which, in the form of theinvention illustrated, is a iii-metallic strip having its end oppositethe contact 52 rigidly secured to a side of the casing 38. An electricalconduit 56 leads from one side of a battery 58 to the intermediatecontact 52 and includes a manually operable switch 68. The opposite sideof the battery 58 is grounded, as indicated at 82. An electrical conduit64 leads from the contact 50 to one side 66 of the split field of areversible electric motor 88 and a similar electric conduit 18 leadsfrom the contact 48 to the opposite side 12 of the split motor field.The curient can pass from either side of the split motor field to therotor of the motor in a manner well known in the art and the side of therotor opposite the field connection is grounded, as indicated at 14, toprovide a complete circuit from the battery through the controllingmechanism to ground and through the ground connections back to thebattery. It is obvious that, if desired, a third wire system may besubstituted for the ground connections schematically illustrated in theaccompanying drawings. Y

the motorrotates in the opposite direction the flaps are moved inwardly.

A limit switch 18 is provided to de-energize the appropriate side of themotor field whenever the motor has moved the flaps 24 to a limitingposition in either direction. This limit switch, as particularlyillustrated in Fig. 3, may con-' veniently comprise a pivotally mountedlever member having one end associated by means of a lost motionconnection with a rod 82 pivotally connected to one of the flaps 24 andhaving its opposite end in contact at opposite sides thereof with a pairof spring contact members 84 and 86. The lost motion connection betweenthe rod 82 and thelever 80 may conveniently comprise adjustableabutments 88 and 90 which are effective to contact the adjacent side ofthe end portion of the lever member 80 when the flap 24 has been movedto the respective limiting position. In the form of the deviceillustrated, when the flap 24 is moved to its outer limiting position,the abutment 90 will contact the lower side of the end portion of thelever member 80 to swing this outer end portion upwardly about the pivot82 and cause the opposite end of the lever member to bear'against thespring contact member 86 and move the contact member away from therespective contact'84, thus breaking the contact between the battery andthe side 68 of the split field of the motor 88. Similarly, when the flap24 has reached its inward limiting position, the abutment 88 contactsthe upper side of the end portion of'the'lever member 80 and causes thelever member to move the spring contact member 84 away from the contact96, thus breaking the circuitto the side 12 of the split field of themotor 68. g 1

The operation of the device is substantially as follows: the casing 38is not air-tight and, therefore, subjects the bellows 32 and 34 which itcontains to the pressure of the air in the cowl compartment at the rearof the engine. The bellows 32 is thus subject to the pressuredifferential be-' tween the front and rear cowl compartments, thepressure in the front compartment acting onthe interior of the bellows,and the pressure on the rear compartment acting upon the exterior. Whenthe pressure in the front compartment is in excess of the pressure inthe rear compartment, the bellows 32 tends to expand and movethe bar 46to bring the contacts and 52 together. Bringing the contacts 50 and 52together completes the circuit through the circuit breaker and throughthe side 66 of the split field of the motor 68 and rotates the motor ina direction to close the cowl flaps 24.

The bellows 34 is subject exteriorly to the pressure in the rear cowlcompartment and interiorly to the pressure in the engine intakemanifold. When theengine throttle is partly closed, thereby reducing thepressure in the manifold, the bellows 34 will be, contracted so that thecontact 50 will be moved toward the contact 52 with the result abovestated. If the engine throttle is open, or nearly open, so that thepressure within the intake. manifold is high, the bellows 34 will beexpanded to move the contact 50 away from the contact 52 and move thecontact 48 towards the contact 52 and, under conditions in which thepressure difierential affecting the bellows 32 is sufiiciently small andthe pressure within the intake manifold 44 is sufliciently high, the bar46 will be moved in a direction tobring the contacts 48 and 52 together.When the contacts 48 and 52 are brought together, the circuit will becompleted through the conduit 10, the limit switch 18, and through theside 12 of the split field of the motor 68, causing the motor to rotatein a direction to open the cowl flaps 24. Thus it will be seen thatunder conditions of a relatively vice will tend to close the cowl flaps.

low pressure differential and relatively high engine horsepower-output.the device will tend to open the flaps and under the oppositeconditions, that is, a relatively high pressure differential andrelatively low engine horsepower output, the de- As the device operatesupon the resultant effect of the pressure diiierential and the enginehorsepower output, it is also obvious that a condition of either one ofthese factors alone above or below a predetermined range may be utilizedto actuate the mechanism asv well as theeiiect of both factors whenacting within a predetermined range.

. The effect of the thermostatic element 54, which is responsive to thetemperature of the air within the rear compartment, is to move theintermediate contact 52 to compensate the controlling mechanism forvariations in the temperature of the cooling air and also to render thedevice to some extent responsive to the temperature of the engine; Thusif the temperature of the air surrounding the thermostatic element ishigh, theelement will be moved toward the contact 48, thereby, renderingit easier for the bellows 32 and 34 to bring the contacts 52 and 48together, with the result that the control device 20 will cause theflaps to open earlier when the air temperatureis high. When the airtemperature is low, the thermostatic element will move the contactdelaying the opening of the cowl flaps when the air temperature is low.

.The limit switch It is effective when have reached their limitingangular position 'in either direction to de-energize the side of thesplit field of the motor tending to rotatethe motor in a direction tomove the flaps further in that direction but leaving the oppositecontact engaged so that upon a reversal of current the motor will beoperative to move the flaps toward the opposite position.

While the control device will tend to move the flaps with each change inthe values of the pressure differential between the forward and rearflap compartments and the pressure within the intake manifold '54, whenthe operation of the engine reachesa stable condition, such for instanceas in cruising at a constant horsepower, the-controLdevice will move theflaps to the appropriate setting for the particular condition and willthen tend to maintain the flaps in that position. Sufllcient space isprovided between the contacts 50, 52, and 48 to provide for minorvariations in the conditions upon which the control is based withoutactuating the control to change the flap setting thus, to a practicaldegree. eliminating the tendency of the device to hunt" when conditionsare relatively stable. Suitable adjustments may obviously be provided toaccommodate the device to various engine and vehicle combinations and toprovide for a desired engine operating temperature.

While there has been illustrated and described a particular mechanicalarrangement of what is now considered to be the preferred form of theidea of the invention, it is to be understood that the invention is notlimited to the construction so illustrated and described but that suchchanges in the size, shape, and arrangement of parts may be resorted toas come within the scope of the appended claims.

Having now described the invention so that others skilled in the art mayclearly understand the same, what it is desired to secure by lettersPatent is as follows. 7

What is claimed is: v

1. In combination with an engine having a plurality of heat radiatingcylinders, a cowling inclosing said cylinders, baflles between saidcylinders to restrict the flow of cooling air through said engine andcreate an air pressure differential within said cowl upon opposite sidesof said bailles, and movable cowl flaps for controlling the air pressureon the low pressure side of said baflies, power operated means effectiveto open and close said cowl flaps, and means responsive to thepressuredrop across said baflles for controlling said power operating means.

2. In combination with an engine having a plurality of heat radiatingcylinders, a cowl inclosing said cylinders, bailies between said cyl-.

flow of cooling air through 52 toward the contact 5., thus air pressuredifler- .erating with said fles and to the power output of said enginefor controlling said power operated means.

3. In combination with an engine having a plurality .of heat radiatingcylinders, a cowl inclosing said cylinders, bailies between saidcylinders to restrict the flow of cooling air through said engine andcreate an air pressure difi'erential within said cowl upon oppositesides of said bafiles, and movab the air pressure on the low pressureside of said baflles, power operated means effective to open and closesaid cowl flaps, and means responsive to the pressure drop across saidbaflles, to the power output of said engine, and to the temperature ofthe air passing through said engine for controlling said power operatedmeans.

4. In combination with an air cooled engine, a cow] surrounding saidengine, means coopengine dividing said cowl into a high air pressurechamber and a low air pressure chamber, and means for controlling thecooling of said engine by controlling the air pressure in .said low airpressure chamber, means responsive to the pressure difierence of the airin said cowl chambers and to the power output of said engine forregulating the cooling of said engine by automatically operating saidcontrol means.

5. In combination with an air cooled engine, a cowl surrounding saidengine, means coopengine dividing said cowl into a high air pressurechamber and a low air pressure chamber, and means for controlling thecooling of said engine by controlling the air pressure in said low airpressure chamber, means responsive to the pressure diiferenceoi' the airin said cowl chambers, to the power output of said engine, and to thetemperature of the air passing through said engine for regulating thecooling of said engine by automatically operat ing said control means. I

6. In combination with an air cooled engine, a cowl-surrounding saidengine, means cooperating with said engine dividing saidcowl into a highair pressure chamber and a low air pressure chamber, and means forcontrolling the cooling of said engine by controlling the air pressurein said low air pressure chamber comprising, power operated means foroperating said control means, and means responsive to the pressuredifference of the air in said cowl chambers, to the power output of saidengine, and to the temperature of the air passing through said enginefor regulating the cooling of said engine by actuating said poweroperated means to automatically operate said control means.

7. In combination with an air cooled engine,

,. a, cowl surrounding said engine, means coopcrating with said-enginedividing said cowl into pressure in said low air pressure chamber,electrically operated means for operating said con trol means, and meansresponsive to the pressure diiference of the air in said cowl chambers,to the power output of said engine, andto the temperature of the airpassing through said engine for regulating the cooling of said engine byactuating said electrically operated means to automatically operate saidcontrol means.

8. In combination with an air cooled engine, a cowl surrounding saidengine, means cooperating with said engine dividing said cowl into ahigh pressure chamber and a low pressure le cowl flaps for controllingchamber, and means for controlling the cooling of said engine bycontrolling the air pressure in said low air pressure chamber, poweroperated means for operating said control means, and means comprising abellows responsive to the pressure difference of the air in said cowlchambers, and a bellows responsive to the power output of said enginefor controlling said power operated means.

9. In combination with an air cooled engine, a cowl surrounding saidengine, means cooperating with said engine'dividing said cowl into ahigh air pressure chamber and a low air pressure chamber, and means forcontrolling the cooling of said engine by controlling the air pressurein said low air pressure chamber comprising, electrically operated meansfor operating said control means, and means for actuating saidelectrically operated means, said means including a bellows responsiveto the pressure diiference of the air in said cowl chambers, a bellowsresponsive to the power output of said engine, and a switch operated bysaid bellows for actuating said electrically operated means.

10. In combination with an air cooled'engine, a cowl surrounding saidengine, means cooperating with said engine dividing said cowl into ahigh air pressure chamber and a low air pressure chamber, and means forcontrolling the cooling of said engine by controlling the air pressurein said low air pressure chamber comprising electrically operated meansfor operating said control means, and means for actuating saidelectrically operated means, said means comprising a 11. In combinationwith an air cooled engine, a

cowl surrounding said engine, means cooperating with said enginedividing said cowl into a high air pressure chamber and a low airpressure chamber, and means for controlling the cooling of said engineby controlling the air pressure in said low air pressure chamberincluding, a reversible electric motor for operating .said controlmeans, and means for actuating said motor comprising a bellowsresponsive to the pressure diflerence of the air in said cowl chambers,a bellows responsive to the power output of said engine, a two-poleelectric switch operated by said bellows for energizing said motor torotate in either direction depending upon the conditions of the pressurediflerence and power output to which said bellows respond, and athermostatic device responsive to the temperature of the air in said lowpressure chamber for modifying the action of said bellows to operatesaid switch.

12. In combination with an air cooled engine, a cowl surrounding saidengine, means cooperating with said engine dividing said cowl into ahigh air pressure chamber and a low air pressure chamber, and a seriesof movable cowl flaps for controlling the cooling of'said engine bycontrolling the air pressure in said low air pressure chamber, areversible said flaps, and means'for actuatingsaid motor comprising anelement responsive to the pressuredifference of the air in said cowlchambers, an

element responsive to the power output of said electric motor foroperating I 14. In combination with an air cooled engine, a

of the air in said low air pressure chamber, and

a two-pole electric switch operated jointly or independently by saidelements to energize said motor to rotate in a direction correspondingto the cooling requirements of said engine.

13. In combination with an air cooled engine, a cowl surrounding saidengine, means cooperating with said engine dividing said cowl into ahigh air pressure chamber and a low air pressure chamber, and a seriesof movable cowl flaps for controlling the cooling of said engine bycontrolling the air pressure in said low air pressure chamber, areversible electric motor for operating said flaps, and-means foractuating said motor comprising an element responsive to the'pressuredifierence of theair in said cowl chambers, an element responsive to thepower output of said engine, an element responsive to the temperature ofthe air in said low air pressure chamber, a two-pole electric switchoperated jointly or independently by said elements to energize saidmotor to rotate in a direction corresponding to the cooling requirementsof said engine, and a screw jack interposed between said motor and saidflaps.

cowl surrounding said engine,,means cooperating with said enginedividing said cowl into a. high air pressure chamber and a low airpressure chamber, and a series of movable cowl flaps for controlling thecooling of said engine by con trolling the air pressure in said low airpressure chamber, a reversible electric motor for operating said flaps,and means for actuating said motor comprising an element responsive tothe pressure difference of the air in said cowl chambers, an glementresponsive to the power output of said engine, an element responsive tothe temperature of the air in said low air pressure chamber, a twopoleelectric switch operated jointly or independently by said elementsrotate in a direction corresponding'to the cooling requirements of saidengine, a. screw jack interposed between said motor and said flaps, anda limit switch interposed in the circuit between said two-pole switchand said motor for de-energizing said motor to rotate further in thesame 15 to energize said motor to direction when the cowl flaps havereached their limiting position in either direction.

' .o HARRY C. NISSEN.

